A major component of active nonproliferation programs is the disposition of stockpiles of both civilian-generated and military-generated plutonium. Destroying plutonium via fission in nuclear reactors is a preferable means to disposing of it. Furthermore, previously used nuclear fuel can be used as a feed fuel for a variety of nuclear reactor designs. The predominant fissile isotope in both consuming plutonium stockpiles and previously used fuel is plutonium 239 (Pu-239). Additionally, high-burnup fuels designed to maximize uranium utilization benefit from the consumption of plutonium generated in the fuel. There is a need for nuclear reactor designs that are optimized for safe and reliable use of fuels comprising Pu-239.